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  • #1

    Convert from r-12 to r134a

    Have any of you successfully converted from R-12 to R134a. Have a Bm23 that was purchased for 200. Stays at 40 degrees--no lower. Cleaned the evaporator core, changed thermosat--door seals good. Compressor cycles on and off--on about 10 minutes and off for about 15-20. Have concluded it must be low on freon. I am thinking about putting in a some R-12, if I can find a can somewhere--hope that it is a very slow leak and will last a long time before having to add more or maybe just seeing about changing out the freon from 12 to 134a. What would it take besides vaccuming out the system and cleaning with solvent to remove oil in the system. I have seen where it is recommended to change the dryer--don't see a dryer or any other valves--am I missing something.

    Thanks for any advice.
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  • #2
    No need to go to 134a. There are replacement refrigerants for 12 that work just fine. R409a works very well for that application with no need to replace the oil. The system would take about 80% of the original charge of 12.


    THE ICEMAN
    My conversion ===------->> KILLER KEGERATOR
    "Without question, the greatest invention in the history of mankind is beer. Oh, I grant you that the wheel was also a fine invention, but the wheel does not go nearly as well with pizza."
    -Dave Barry-
    "We old folks have to find our cushions and pillows in our tankards.
    Strong beer is the milk of the old."
    -Martin Luther-

    Comment

    • #3
      ICEMAN,

      Thanks for the relpy. Can you add R409a to R12 or do you have to vaccum out the R12 first?
      Is there a good supplier for R409a that you would recommend? Do you agree that it appears the problem is low freon?

      Originally posted by THE ICEMAN View Post
      No need to go to 134a. There are replacement refrigerants for 12 that work just fine. R409a works very well for that application with no need to replace the oil. The system would take about 80% of the original charge of 12.


      THE ICEMAN

      Comment

      • #4
        Added R-12 that my dad had saved and talked to a friend that works on refrigeration equipment and he told me that the low pressure should be around 30psi---now the unit is down around 39 degrees and still running. Line is frosted and I am monitoring it. Hopefully it continues to go down. Will continue to monitor--really like my Bm23 and the Coors Lite--foam is getting less and less as the temp goes down--celebrated Mardi Gras at home. Big event here in Mamou, Louisiana. Riding around the country side on horseback or on a trailer, chasing chickens, drinking, and eating gumbo--life is good!! Tomorrow is Ash Wednesday and starts lent--looking forward for Easter.
        Last edited by tsoileau; 02-16-2010, 07:36 PM.

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        • #5
          Originally posted by tsoileau View Post
          Added R-12 that my dad had saved and talked to a friend that works on refrigeration equipment and he told me that the low pressure should be around 30psi---now the unit is down around 39 degrees and still running. Line is frosted and I am monitoring it. Hopefully it continues to go down. Will continue to monitor--really like my Bm23 and the Coors Lite--foam is getting less and less as the temp goes down--celebrated Mardi Gras at home. Big event here in Mamou, Louisiana. Riding around the country side on horseback or on a trailer, chasing chickens, drinking, and eating gumbo--life is good!! Tomorrow is Ash Wednesday and starts lent--looking forward for Easter.
          If you have frost coming back to the compressor when the unit is down to temp you are overcharged. The closest the frost should be is 8 to 10 inches away from the compressor.
          When frost is coming all the way back to the compressor it means liquid refrigerant could get into the valves & warp them. The charge needs to be backed off. You will find the unit cools more efficiently.


          THE ICEMAN
          My conversion ===------->> KILLER KEGERATOR
          "Without question, the greatest invention in the history of mankind is beer. Oh, I grant you that the wheel was also a fine invention, but the wheel does not go nearly as well with pizza."
          -Dave Barry-
          "We old folks have to find our cushions and pillows in our tankards.
          Strong beer is the milk of the old."
          -Martin Luther-

          Comment

          • #6
            Originally posted by THE ICEMAN View Post
            If you have frost coming back to the compressor when the unit is down to temp you are overcharged. The closest the frost should be is 8 to 10 inches away from the compressor.
            When frost is coming all the way back to the compressor it means liquid refrigerant could get into the valves & warp them. The charge needs to be backed off. You will find the unit cools more efficiently.


            THE ICEMAN
            Frost only appears while the unit is running. Talked to a friend who works on cooling units and he told me that the low side should be around 30 lbs. Unit is now between 25 and 30 and is cooling better. Compressor runs a lot longer than before and temp is dropping--slowly. Frost comes about 3 to 4 inches from compressor then goes away when unit stops--does this seem correct.

            Thanks for your advise.

            Comment

            • #7
              The pressure will drop as the temperature comes down. Temp & pressure are directly related. Your pressure should be close to 17-20 psi at the point of shut off.
              You should be ok with the frost although I would be tempted to back it off just a bit more.


              THE ICEMAN
              My conversion ===------->> KILLER KEGERATOR
              "Without question, the greatest invention in the history of mankind is beer. Oh, I grant you that the wheel was also a fine invention, but the wheel does not go nearly as well with pizza."
              -Dave Barry-
              "We old folks have to find our cushions and pillows in our tankards.
              Strong beer is the milk of the old."
              -Martin Luther-

              Comment

              • #8
                Thanks Iceman. Appreciate the help. Will put the gauges back on and see what the pressure is now that the temp has dropped. Will back it off to 20 if needed.

                ted

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                • #9
                  Iceman,

                  Backed off the pressure to 19 and the suction line frosts over--no longer covered with ice--but, the temp of the beer also went up. I have the thermostat set at 9 and the internal temp is around 39. (Before backing off, the temp was around 36). Beer poured out of the tap is around 39 also. I was worried about having liquid back into the compressor when the suction line had ice on it but now am worried that the unit isn't charged enough. Have already changed the therm. so I would think that this is not a problem. Any suggestions--thanks.

                  Comment

                  • #10
                    Originally posted by tsoileau View Post
                    Iceman,

                    Backed off the pressure to 19 and the suction line frosts over--no longer covered with ice--but, the temp of the beer also went up. I have the thermostat set at 9 and the internal temp is around 39. (Before backing off, the temp was around 36). Beer poured out of the tap is around 39 also. I was worried about having liquid back into the compressor when the suction line had ice on it but now am worried that the unit isn't charged enough. Have already changed the therm. so I would think that this is not a problem. Any suggestions--thanks.
                    You should have a good cold sweat on the suction line or at the very least a cold to the touch line, not frost & certainly not ice next to the compressor. And all that setting the temp control does is make the compressor run longer potentially causing the evaporator coils to frost over. Setting it colder doesn't make it magically colder. Being overcharged is just as bad, as far of performance, as being undercharged. Those type of units are regarded as "critical charge" meaning they take a very specific amount of refrigerant. Any deviation from what is called for hurts performance.


                    THE ICEMAN
                    My conversion ===------->> KILLER KEGERATOR
                    "Without question, the greatest invention in the history of mankind is beer. Oh, I grant you that the wheel was also a fine invention, but the wheel does not go nearly as well with pizza."
                    -Dave Barry-
                    "We old folks have to find our cushions and pillows in our tankards.
                    Strong beer is the milk of the old."
                    -Martin Luther-

                    Comment

                    • #11
                      You can convert from R-12 to R134a with no problem. Just make sure you change the oil of the compressor too. Check Top-refrigerants for details.
                      Last edited by martinh; 09-18-2019, 02:03 AM.

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